White blueish smoke

[81lly]

Hi guys,
I’ve a white blueish smoke from the exhaust when I give it a rev after idling for a minute. I can’t tell if it smokes when accelerating or decelerating.
The only mods are it has a decat and an intake and after scanning vcds it comes back with the following codes
P0420
Raw code: 0420
ECU: Engine control unit
Status: Confirmed
OBDII: Catalytic converter system, bank 1 - efficiency below threshold
Volkswagen: Catalyst System Low Efficiency

============2==============
P0441
Raw code: 0441
ECU: Engine control unit
Status: Pending
OBDII: Evaporative emission (EVAP) system - incorrect flow detected
Volkswagen: Evaporative Emission Control System Incorrect Purge Flow

I know the first one will be because of the decat and the p0441 code will probably be the charcoal canister or the n80 valve. I’m replacing the n80 valve this week but I don’t think either of these is causing the car to smoke.

The car drives fine and I was planning on doing the following for maintenance
Inlet valve walnut blast and injector clean
Engine flush
Replace oil pickup pipe and clean sump
Cam follower
Full service

Before I do any of the above I want to sort the smoke issue, do you think the turbo is on it’s way out or would it be something else? What checks/tests would I need to do?

[pudding]

If the smoke is white, it's likely the turbo as oil is going straight into the turbine housing and evaporating into a white haze.

Oil burned within the cylinders is more of a blue colour.

Or if you're unlucky, both is happening.

Another test for valve guides is to over run the engine down as long a hill as possible, change down a gear at the bottom and boot it.  If you get a cloud of blue behind you, it's the guides.

All of the above assumes the OEM PCV system is fitted and working properly.

[81lly]

If the smoke is white, it's likely the turbo as oil is going straight into the turbine housing and evaporating into a white haze.

Oil burned within the cylinders is more of a blue colour.

Or if you're unlucky, both is happening.

Another test for valve guides is to over run the engine down as long a hill as possible, change down a gear at the bottom and boot it.  If you get a cloud of blue behind you, it's the guides.

All of the above assumes the OEM PCV system is fitted and working properly.

PCV was replaced couple months ago by previous owner apparently, I did the dipstick test so I think the pcv is ok. I also tried your test of going downhill then booting at the bottom, I didn’t notice any smoke so I’m hoping it’s just the turbo.
I’ve booked it in to see what they can find. Will update next week.

[pudding]

It's looking like the prime suspect then.  Let us know how it goes!

[81lly]

Not good news today..

[pudding]

Ask what colour the swarf is how much there is. If it's small gold/brass flecks, it's turbo bearings breaking up.  If it's silver or copper coloured swarf, that is engine bearings.

Hopefully it's just the turbo as that's an £800 fix plus labour, versus £1000s for a new engine/rebuild.

[81lly]

Ask what colour the swarf is how much there is. If it's small gold/brass flecks, it's turbo bearings breaking up.  If it's silver or copper coloured swarf, that is engine bearings.

Hopefully it's just the turbo as that's an £800 fix plus labour, versus £1000s for a new engine/rebuild.

I’ll find out tomorrow

[81lly]

They’ve said it’s the engine and not the turbo, it was a mixture of metallic metal swarf

[pudding]

Bugger. Oil starvation by the sounds of it then.